A number of growth hormones for fishes to mammals has been currently isolated and many of them has been elucidated in regard to even the structure of genes thereof, as there growth hormones could have a growth promotion effect so that they are expectable to be applied to growth promotion of fishes and domestic animals, increase in their edible portions in the field of fish farming and livestock raising. And further a growth hormone has been developed in human beings to exert such effects as usefulness in the treatment of dwarfism or nanism, upon which there have been made research and developement to obtain in large amount of such a growth hormone.
However, it was maintained in the report by T. Bistrizer et al. (The Lancet, 13, 321-323 (1988)) and other that there could be present other growth factors than growth hormones, in view of the presence of individuals showing a normal growth even under a deficient condition of growth hormones.
Then, the present inventors have made earnest studies upon their considerations that there may be found any growth factor having a higher effect than the prior growth hormones or any hormone having new physiological activities, and that there may be not only a great scientific development but also a higher industrial usefulness if such a substance could be found and obtained in a large amount. As a result of these studies, they have found out a novel growth hormone-like glycoprotein from the pituitary gland of flounder or halibut and further developed a process for producing the same in a large amount, with a successful cloning of the gene coding the amino acid sequence of such a growth hormone-like glycoprotein.